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Fix potential stall on HTTP/2 connection #6367

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Fix potential stall on HTTP/2 connection #6367

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85 changes: 21 additions & 64 deletions proxy/http2/Http2Stream.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -95,42 +95,17 @@ Http2Stream::main_event_handler(int event, void *edata)
case VC_EVENT_ACTIVE_TIMEOUT:
case VC_EVENT_INACTIVITY_TIMEOUT:
if (_sm && read_vio.ntodo() > 0) {
MUTEX_TRY_LOCK(lock, read_vio.mutex, this_ethread());
if (lock.is_locked()) {
read_vio.cont->handleEvent(event, &read_vio);
} else {
if (this->_read_vio_event) {
this->_read_vio_event->cancel();
}
this->_read_vio_event = this_ethread()->schedule_imm(read_vio.cont, event, &read_vio);
}
this->_signal_event(this->read_vio, event);
} else if (_sm && write_vio.ntodo() > 0) {
MUTEX_TRY_LOCK(lock, write_vio.mutex, this_ethread());
if (lock.is_locked()) {
write_vio.cont->handleEvent(event, &write_vio);
} else {
if (this->_write_vio_event) {
this->_write_vio_event->cancel();
}
this->_write_vio_event = this_ethread()->schedule_imm(write_vio.cont, event, &write_vio);
}
this->_signal_event(this->write_vio, event);
}

break;
case VC_EVENT_WRITE_READY:
case VC_EVENT_WRITE_COMPLETE:
inactive_timeout_at = Thread::get_hrtime() + inactive_timeout;
if (e->cookie == &write_vio) {
if (write_vio.mutex && write_vio.cont && this->_sm) {
MUTEX_TRY_LOCK(lock, write_vio.mutex, this_ethread());
if (lock.is_locked()) {
write_vio.cont->handleEvent(event, &write_vio);
} else {
if (this->_write_vio_event) {
this->_write_vio_event->cancel();
}
this->_write_vio_event = this_ethread()->schedule_imm(write_vio.cont, event, &write_vio);
}
}
if (this->_sm && e->cookie == &write_vio) {
this->_signal_event(this->write_vio, event);
} else {
update_write_request(write_vio.get_reader(), INT64_MAX, true);
}
Expand All @@ -139,17 +114,7 @@ Http2Stream::main_event_handler(int event, void *edata)
case VC_EVENT_READ_READY:
inactive_timeout_at = Thread::get_hrtime() + inactive_timeout;
if (e->cookie == &read_vio) {
if (read_vio.mutex && read_vio.cont && this->_sm) {
MUTEX_TRY_LOCK(lock, read_vio.mutex, this_ethread());
if (lock.is_locked()) {
read_vio.cont->handleEvent(event, &read_vio);
} else {
if (this->_read_vio_event) {
this->_read_vio_event->cancel();
}
this->_read_vio_event = this_ethread()->schedule_imm(read_vio.cont, event, &read_vio);
}
}
this->_signal_event(this->read_vio, event);
} else {
this->update_read_request(INT64_MAX, true);
}
Expand Down Expand Up @@ -664,19 +629,7 @@ Http2Stream::update_write_request(IOBufferReader *buf_reader, int64_t write_len,
void
Http2Stream::signal_read_event(int event)
{
if (this->read_vio.cont == nullptr || this->read_vio.cont->mutex == nullptr || this->read_vio.op == VIO::NONE) {
return;
}

MUTEX_TRY_LOCK(lock, read_vio.cont->mutex, this_ethread());
if (lock.is_locked()) {
this->read_vio.cont->handleEvent(event, &this->read_vio);
} else {
if (this->_read_vio_event) {
this->_read_vio_event->cancel();
}
this->_read_vio_event = this_ethread()->schedule_imm(read_vio.cont, event, &read_vio);
}
this->_signal_event(this->read_vio, event);
}

void
Expand Down Expand Up @@ -899,16 +852,6 @@ Http2Stream::clear_io_events()
buffer_full_write_event->cancel();
buffer_full_write_event = nullptr;
}

if (this->_read_vio_event) {
this->_read_vio_event->cancel();
this->_read_vio_event = nullptr;
}

if (this->_write_vio_event) {
this->_write_vio_event->cancel();
this->_write_vio_event = nullptr;
}
}

void
Expand Down Expand Up @@ -989,6 +932,20 @@ Http2Stream::decrement_server_rwnd(size_t amount)
}
}

/**
Signal @event to @vio.cont
*/
void
Http2Stream::_signal_event(VIO &vio, int event)
{
if (vio.cont == nullptr || vio.cont->mutex == nullptr || vio.op == VIO::NONE) {
return;
}

SCOPED_MUTEX_LOCK(lock, vio.cont->mutex, this_ethread());
vio.cont->handleEvent(event, &vio);
}

bool
Http2Stream::_switch_thread_if_not_on_right_thread(int event, void *edata)
{
Expand Down
8 changes: 3 additions & 5 deletions proxy/http2/Http2Stream.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -148,7 +148,7 @@ class Http2Stream : public ProxyTransaction
bool response_is_data_available() const;
Event *send_tracked_event(Event *event, int send_event, VIO *vio);
void send_response_body(bool call_update);

void _signal_event(VIO &vio, int event);
/**
* Check if this thread is the right thread to process events for this
* continuation.
Expand Down Expand Up @@ -216,10 +216,8 @@ class Http2Stream : public ProxyTransaction
ink_hrtime inactive_timeout_at = 0;
Event *inactive_event = nullptr;

Event *read_event = nullptr;
Event *write_event = nullptr;
Event *_read_vio_event = nullptr;
Event *_write_vio_event = nullptr;
Event *read_event = nullptr;
Event *write_event = nullptr;
};

extern ClassAllocator<Http2Stream> http2StreamAllocator;
Expand Down